1. Field of the Invention:
The present invention relates to novel surface-active compositions which are synergistically active vis-a-vis the individual constituents thereof and to the production of such compositions. The invention also relates to the use of said compositions in the formulation of various active agents in the form of wettable powders or granular materials; it too relates to aqueous or organic dispersions of active materials produced from said wettable powders or granular materials.
2. Description of the Prior Art:
In many fields of use, such as phytopharmacy, the building industries, and the painting and paper, textile, cosmetics, etc., industries, there is a need to prepare aqueous or organic dispersions of active materials, or active agents, which are insoluble or difficult to dissolve in water and which are in finely divided form. By the term "active materials" is intended both pigments and coloring agents, optical bluing agents, additives for plastics and paints, adjuvants for textiles, adjuvants for concretes, cosmetic products, biocidal compounds, more particularly active agents for phytopharmaceutical applications such as herbicides, fungicides, insecticides, acaricides or any other biocidal agent having phytopharmaceutical activity, and the like.
Active materials of such nature, which are employed in the form of suspensions upon actual use thereof may be in the form of wettable powders or in the form of granular materials. Such formulations in most cases include one or more active materials, one or more surface-active agents, fillers and possibly auxiliary substances, or adjuvants.
The active material comprising the formulation is insoluble in water or very difficult to dissolve. It occurs either in solid form or in liquid form. In such latter case, it is necessary for it to be absorbed onto a suitable carrier.
However, having regard to the diversity of active materials having a preponderant hydrophobic character and the nature of the dispersing agent, which in most cases is water, a certain amount of difficulty is involved in selecting a satisfactory surface-active agent. The choice of the surface-active agent is made difficult by the existence of a large number of parameters to be observed.
In order to have a good formulation for the active material, the surface-active agent must not display any incompatibility with the latter and it must present a good binding and film-forming capacity in order to produce granular materials having a very high proportion of active material. It must also be ensured that the active material enjoys a high level cf stability in the course of storage and, in particular, the formation of lumps in the wettable powder or the formation of fines in the granular materials must be prevented.
In the preparation of the dispersion of the active material, which is also referred to as "slurry", the surface-active agent must have a good wetting capacity in order to properly wet the active material and a good dispersant capacity in. such a fashion that the active material is properly dispersed in the water and the dispersion produced is homogenous and stable for at least the time of application thereof without causing any secondary problems, such as, for example, the formation of foams, or flocculation which may cause blockage of the nozzles of the spraying equipment, and if ever settlement should occur over the course of casual storage prior to use of the materials, it is desirable that the active material revert very easily to the form of a dispersion.
Finally, upon using the material and more particularly in the case of phytopharmaceutical use thereof, the surface-active agent can promote improved availability of the active material: improved wettability of the portions of the plant which are to be treated, and better penetration into the plants.
As will be clearly apparent from the foregoing, it is very difficult to identify a surface-active agent, or a surface-active system, which satisfies all of the requirements outlined above.
French Pat. No. 2,397,444 describes that, in order to prepare stable and concentrated dispersions of active materials in the form of non-dusting powders or granular materials, it is necessary to separate the active material in the presence of a salt of an acidicresin, such as, for example, a copolymer of maleic anhydride and an .alpha.-olefinic compound; add an organic solvent which forms, together with the aqueous medium, a two-phase system; treat such two-phase system by adding a carrier substance thereto; and then isolate the product by a reduction in the volume of the organic phase by the addition of water, the solvent gradually transferring into the added water.
It has now been determined that the use of an acidic resin as described above is not entirely satisfactory, particularly when using active materials which are difficult to formulate, because the dispersability thereof is unsatisfactory and flocculation and/or settlement occur between the time of preparation of the slurry and the use thereof in the technical area in question.